Explosionproof lamp fitting



Feb. 9, 1943. w. NERLICH EXPLOSION-PROQF LAMP FITTING Filed Sept. 10, 1940 2 Sheets-Sheet 1 WIT-NESSES:

Feb.l 9, 1943. w..\NER| lcH EXPLOSION-PROOF LAMP FITTING Filed Sept. 1o, 1940 2 sheetS-sheet'z INVENTOR W/'l/f Ner/l'c /7.

WITNESSES.

Patented Feb. 9, 1943 EXPLOSIONPROF LAMP FITTING Willi Nerlich, Berlin-Spandau, Germany, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 10, 1940, Serial No. 356,121 In Germany August 30, 1939 3 Claims.

This invention relates to explosion-proof lamp iittings. Such lamp fittings consist of a casing, bottom part, a glass globe and o-f a wire guard for the glass globe. The Wire guard is, as a rule, secured to a ring which is attached to the lamp casing by means of a bayonet locking or the like. To secure the bayonet locking or the like triangular screws are employed which either exert a pressure on the ring at the side or from above or which pass through the same in any suitable manner. These arrangements have, however, the drawback that they do not operate automatically so that the position of the wire guard and glass globe is not ensured if it has been inadvertently omitted to actuate the screws.

In the case of an explosion-proof lamp fitting in which the globe and the wire guard are secured to the Icasing by means of a 4bayonet locking, the opening cf the bayonet locking is prevented according to the invention by means of a locking device consisting of a notched segment and a resilient catch and is only possible when the resilient catch is released.

Before removing the wire guard and the glass globe a particular operation is necessary when using the arrangement according to the invention. r`Ehe release is preferably eiected not by the use of a handle but by means of a tool, for instance, of a socket wrench.

These lamp ttings present a disadvantage in that it is possible to assemble the lamp fitting when the resilient catch is released. In this case when the lamp tting is assembled the resilient catch is not actuated and the lamp tting presents the same drawbacks as the lamp ttings described above. It is therefore advisable to provide a means for the lamp tting with the aid cf which when removing the wire guard with the ring and bayonet parts the resilient catch is automatically brought into engagement. This may be attained in an eicient manner bythe fact that the release of the resilient catch is effected with the aid of a cam shaft which may be operated exteriorly of the lamp casing with the aid of a tool, for instance, of a socket Wrench. If the shaft is provided with a cam or a lug and the ring of the casing with the bayonet parts is provided with a corresponding lug, the lug of the bayonet ring rotates the cam shaft, when the bayonet ring is being removed, to such an extent that the release of the resilient catch is counteracted. With the bayonet part removed the resilient catch is therefore in the normal position and when inserting again the bayonet part the resilient catch must come into engagement with the notched segment. If the bayonet ring is to be again removed it is necessary to rotate the cam shaft to such an extent that the resilient catch comes out of engagement.

In the accompanying drawings are shown some embodiments of the invention in'rdiagrammatic form in which like numerals denote corresponding parts in all views of which:

Figure 1 is a side View in elevation of a lamp `fitting embodying the principal features of the invention;

Fig. 2 is a cross-section View in elevation along line II-II of Fig. 1;

Fig. 3 is a top plan View of the casing only of thedevice of Fig. 1;

Fig. 4 is a cross-section View of the wire guard along line IV-IV of Fig. 2;

Fig. 5 is a perspective vieW of a socket wrench;

Fig. 6 is a detail perspective View of the upper edge of the lamp casing of Fig. 1 showing details of the bayonet connecting parts thereon and the arrangement for locking the wire guard to the lamp casing;

Fig. 7 is a detail perspective View of the wire guard showing details of the notched segment portion of the locking arrangement and the bayonet parts I2 on the bayonet ring portion of the wire guard;

Fig. 8 is a detailed perspective View similar to Fig. 6 showing the relative positions of the various elements of the locking arrangement;

Fig. 9 is a detailed perspective view of a modii'lcaticn of the invention shown in Figs. 1

rthrough 8, particularly with respect to the locking arrangement; and

Fig. 10 is a partial side view in elevation of Fig. 9 showing the position of the notched segment portion of the locking arrangement.

Fig. 1 shows an assembled lamp tting. It consists of the bottom part I with the connection branch 2 and of the end 3 of the cam shaft. In this embodiment the end of the cam shaft is of a triangular cross-section on which iits a corresponding socket wrench 4 as shown in Fig. 5. On the lamp casing I is arranged the bayonet ring 4 with the wire guard 5. The bayonet ring 4 holds at the same time the glass globe 6 in position.

In Figs. 2 to 4 are shown schematically the individual parts. On the shoulder 'I of the lamp casing l is arranged by interposition of a rubber ring 9 of U-shaped cross-section a flange 3 of the glass globe 6. On the rubber` ring 9 is arranged the bayonet ring 4 provided with the lugs lo, Il and I2. The casing I has corresponding bayonet parts I3, I4 and l5. In the neighborhood .of the bayonet part I2 of the ring 4 there is arranged a notched segment I6. In the casing I is provided a resilient catch Il with a perforation I8 and an inclined surface I9. In Fig. 6 is schematically shown the nc-tched segment I5. A cam 2li which rotates about the shaft 2| exerts a pressure on the resilient catch Il. The shaft 2| is extended outwardly and its end is, for instance, of a triangular cross-section on which fits the socket Wrench 4'. In Fig. 6 is shown in dotted lines the notched segment I6 resting on the ring 4. As will be seen from Fig. 6 the cam 20 presses the resilient catch I1 in the downward direction to such an extent that the teeth of the notched segment are out of engagement with the perforation I8. In this position the notched segment may, therefore, be moved over the resilient catch and the bayonet ring 4 may be removed. On the shaft 2| preferably integral with the cam there is, however, provided another cam 22. When removing the bayonet ring 4 the part 23 of the notched segment I6 bent at right angles comes into engagement with the cam 22 so that the shaft 2I is rotated and the two cams 20 and 22 reach the position shown in Fig. 8. Owing to the springiness of the catch I1 the latter is brought into the locking position. As will be apparent from Fig. 8 the inclined surface 24 of the notched segment IS may come into engagement with the inclined surface I9 of the resilient catch I1 so that upon the movement of the notched segment in the direction as indicated by the arrow the teeth may snap into the perforation I8. The bayonet ring 4 with the notched segment I6 is rotated to the greatest possible extent. A spring action is attained by the rubber ring 9. The resilient catch I1 prevents a removal of the bayonet ring. Only when the shaft 2| with the cams 20 and 22 is rotated by 90 the cam 20 exerts a downward pressure on the resilient catch I1 to such an extent that the notched segment is released, thus enabling a removal of the bayonet ring. When removing the bayonet ring the lug 23 of the notched segment I6 comes as described above into engagement with the cam 22 so that the catch I1 is again brought into the locking position and the lamp may be reassembled.

The locking device may also be designed as shown in Figs. 9 and 10. The teeth of the notched segment 25 do not extend in the vertical direction but laterally of the segment 25. On the casing I is arranged a resilient catch 2B Whose free end 21 may be brought into engagement with the teeth of the notched segment 25. A shaft 28 which may be rotated exteriorly of the casing, for instance, by means of a Wrench extends through the casing I. On the shaft 2I is mounted a pin 29. If the shaft is rotated in the direction of the arrow the catch 26 is released and pressed against the casing I. A second pin 30 is also mounted on the shaft 28. If the bayonet ring 4 of the lamp fitting with the catch 26 released is rotated out of the casing I, the stop pin 3l of the bayonet ring 4 comes into engagement with the pin 30 and rotates the shaft in the opposite direction so that the catch 26 is moved away from the casing I and may come into engagement with the notched segment 25 when replacing the bayonet ring.

What is claimed is:

1. The combination in an explosion-proof lighting fixture having a casing member to which a globe is secured by a ring member attached to the casing by means of a bayonet locking arrangement. of a notched segment member attached to the ring member, a spring member attached to the casing adapted to releasably engage the notched segment member to lock the ring member to the casing, and cam means mounted on the casing in co-operative relation with the spring member and operable in one direction from without the casing for releasing the spring member from engagement with the notched segment member and holding it out of engagement therewith while the ring member is being detached from the casing, and means carried by the ring member for actuating the cam means in the opposite direction to permit the spring member to return to its normal locking position when the ring member reaches such position as it may be removed from the casing.

2. An explosion-proof lamp fitting comprising, a cup-shaped casing, a dome-shaped globe mounted on the casing, a ring member engaging the casing by means of a bayonet locking arrangement for retaining the globe in position thereon, and means for releasably locking the ring member to the casing including a notched segment attached to the ring member, a resilient catch member attached to the casing having a normal locking position where it engages the notched segment when the ring member is attached to the casing to prevent said ring member from being removed, and cam means rotatably mounted in the casing in operative relation with the resilient catch member and operable from a normal operating position from outside the casing to release the resilient catch member from engagement with the notched segment, said cam means functioning when operated to hold the resilient catch member in a disengaged position while the ring member is being detached by rotating it with respect to the casing, said notched segment having a bent end portion disposed to engage a portion of the cam means to actuate it back to its normal operating position thereby to release the resilient catch member to its normal locking position when the ring member reaches such position on the casing that it may be removed.

3. An explosion-proof lamp fitting comprising, a cup-shaped casing having a rim portion, a dome-shaped globe mounted on the casing, said globe having an outwardly extending flange portion adjacent the open end thereof, a ring member positioned ,on the globe above the fiange portion for attaching the globe to the casing, said casing and ring member having cooperating members thereon forming a bayonet joint arrangement for clamping the globe to the casing, a multi-notched segment attached to the outside of the ring member, said segment having an outwardly extending end portion, a flat spring member attached to the casing having one end bent upwardly and provided with an aperture therein to engage the teeth of the notched segment and lock therewith when the ring member is rotated into locking engagement with the casing, and cam meansl rotatably mounted in the rim portion of the casing adjacent the flat spring member ,and operable exteriorly of the casing for depressing the spring member and retaining it out of engagement with the notched segment, said cam means having a portion positioned in the path of the outwardly extending end portion of the notched segment, whereby the cam means is actuated to release the spring member when the ring member reaches a position where it may be disengaged from the casing.

WILLI NERLICH. 

